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284871 (2) [Avatar] Offline
#1
Several illustrations of multiple-foci force layouts on bl.ocks.org and elsewhere use an on tick handler that accepts a parameter e, and then use e's component e.alpha without explanation. Apart from the d3 source code (which I haven't looked at), the meaning of e parameter and alpha in this context apparently haven't been documented on the web except in one place that I've found, a StackOverflow answer that's not easily found through Google. I searched the v9 MEAP edition of D3.js in Action and didn't find any documentation on e or e.alpha. I don't know whether any other D3 books cover this, but it seems very worthwhile to consider adding a brief discussion of multiple-foci force layouts and e.alpha to D3.js in Action. Given the existing material on force layouts in the book, this addition would only require a paragraph or a page or two.
elijah.meeks (127) [Avatar] Offline
#2
I wanted to get into multi-foci force layouts, but just didn't have the time or space. It'll have to wait for D3.js in Action 2: The Search for More Information Visualization.

Thanks for the link, though. You might want to try to integrate it into the wiki (or I might). It makes it significantly easier for new users of the library when those details are readily available.
284871 (2) [Avatar] Offline
#3
I understand. Can't do everything.

Amelia Bellamy-Royds added a line about e.alpha to the wiki after she answered my StackOverflow question--soon after I posted my suggestion here. I'm happy that there's something about e.alpha on the wiki now. That information added is pretty terse, but the wiki is supposed to provide documentation rather than recipes. ABR's answer on SO is the sort of thing that's needed to understand e.alpha's use. (I still consider myself a D3 novice, and don't know that I feel that I have sufficient depth of knowledge or a sense of what's appropriate on the wiki to add anything to what ABR added to the wiki. Until recently I thought that it was all written by Mike Bostock, even though it's called a "wiki".)